When adjusting control parameters in a motor control device, it is necessary to set control parameters, such as feedback gain, feedforward gain, and a notch filter within the motor control device, in accordance with mechanical load connected to a motor before actual operation in which the device is actually running.
For example, when adjusting the feedback gain, the feedback gain needs to be set as large as possible in order to increase response of a machine. However, a signal at a resonance point of the machine may be excited as the feedback gain is set larger, and hence oscillation occurs in a torque command, which is a control status amount, or a detection position or speed of the motor, leading to an oscillatory state. Therefore, the feedback gain needs to be set within a range in which the control status amount does not oscillate and the motor is stably operable.
Further, when adjusting the notch filter, in a case where oscillation occurs in the control status amount in the above-mentioned adjustment of the feedback gain, the notch filter is set so as to cut off a component of an oscillatory frequency. In this manner, the oscillation at the oscillatory frequency can be suppressed, with the result that the feedback gain can further be increased.
Further, when adjusting the feedforward gain, the feedforward gain needs to be set as large as possible in order to increase the response of the machine. However, setting the feedforward gain larger leads to oscillation of a positional deviation, which is the control status amount. Therefore, the feedforward gain needs to be set within a range in which an overshoot amount in a stopping state satisfies target performance.
When adjusting those control parameters manually, it is necessary to repeat such trial and error that the machine is operated every time the control parameters are changed and, the response thereof is determined. Thus, a large amount of time and effort are required therefor.
Meanwhile, there are known conventional technologies for adjusting the control parameters in a simple manner, which are described in JP 4150892 B (Patent Document 1), JP 2005-332213 A (Patent Document 2), and JP 2004-192448 A (Patent Document 3).
Patent Document 1 discloses the following motor control device. A command pattern having a trapezoidal wave or a triangular wave for accelerating and decelerating the motor is generated in the motor control device based on parameters input through the parameter input device, which is an external input/output device, and a continuous operation pattern for adjustment, in which the command pattern is repeated a set number of times, is generated and output to operate the machine. Thus, the control parameters are adjusted.
Patent Document 2 discloses the following motor control device. When an activation operation is performed by using the push button or switch of the motor control device, an activation signal is transmitted to the automatic operation function unit. Based on parameters set in the parameter setting unit, a position command for reciprocating the load device (corresponding to the continuous operation pattern for adjustment) is generated and, the gain is automatically adjusted by the gain operation unit.
Patent Document 3 discloses the motor control device that is provided with the steps of: decreasing, by the adjustment unit, the gain when it is determined that excessive deviation abnormality occurs or that operation completion signal abnormality occurs while the operation is repeated in accordance with the control command amount generated by the command generator, and performing the operation again; and determining, when the operation completion signal is normal, whether or not the stabilization time is shorter, and when the stabilization time is shorter than in the previous operation or at the time of the first operation, recording the stabilization time, increasing the gain, and performing the operation again. When there is no reduction in stabilization time through repetition of the above-mentioned steps, the adjustment is completed. Thus, the adjustment is performed automatically.